The present invention relates to a device for measuring the level of a liquid in a radioactive enclosure.
It is known to measure the level of a liquid or solid substance within an enclosure by means of one or more radioactive source vertically positioned outside the enclosure at different levels, as well as detectors located on the opposite wall of the enclosure which receives the radiation coming from the said sources. The absorption level of the radiation emitted by these sources has an attenuation level which varies with the traversed material. The level of the substance in the enclosure is deduced from the intensity of the radiation measured by the detectors positioned along the enclosure wall.
U.S. Pat. No. 3,100,841 describes a device for measuring the level of the charge in a blast furnace and which operates according to this principle. It has a series of level indicators, each of which is constituted by a radioactive source, a detector and a pilot light. The radioactive sources are arranged along a vertical line on the blast furnace. The detectors are located along a vertical line diametrically opposite to the first line. Each radioactive source is located at the bottom of a cylindrical collimating well. The detector, constituted by a G-M counter, is also located on the bottom of a cylindrical well in such a way that the sensitive part of the counter or tube is exposed to the radiation of the diametrically opposite source. Each detector is only sensitive to the radiation coming from the source associated therewith as a result of a collimating device. Means are provided for recording a reading when the detected radiation level exceeds a given level. The charge level in the blast furnace is calculated therefrom.
However, a measuring device as described hereinbefore is not suitable for measuring the level of a liquid contained in a radioactive enclosure. Thus, the activity of this liquid swamps the radioactivity coming from radioactive sources, making it impossible to measure the level of said liquid.